function f(){
	document.getElementById("f").classList.add("selected");
	document.getElementById("s").classList.remove("selected");
	document.getElementById("t").classList.remove("selected");
	document.getElementById("basic_nextstep").innerText="下一步";
}
function s(){
	document.getElementById("s").classList.add("selected");
	document.getElementById("f").classList.remove("selected");
	document.getElementById("t").classList.remove("selected");
	document.getElementById("basic_nextstep").innerText="下一步";
}
function t(){
	document.getElementById("t").classList.add("selected");
	document.getElementById("s").classList.remove("selected");
	document.getElementById("f").classList.remove("selected");
	document.getElementById("basic_nextstep").innerText="下一步";
}